For FY18, we have used multi-dimensional NMR, X-ray crystallography, site-directed mutagenesis coupled with isothermal titration calorimetry to study how nucleosomes and histones are recognized by other proteins. We have determined the cryo-EM structure of the centromere nucleosome core particle bound to the centromere protein CENP-N. We also showed that the reconstituted nucleosome arrays condensed by linker histones or salt have a dynamic structure, which has implications for the structure and function of chromatin in vivo.